Turbocharged engines may provide for greater fuel economy and lower carbon dioxide emission from motor vehicles by allowing for smaller and light engines to be used. These engines generally include direct injection and exhaust gas circulation. Turbocharging the engines may generate more heat, which may increase the operating temperature of the lubricant.
One example to address the increase in heat generated from turbocharged engines to reduce the temperature of the lubricant is to use an oil cooler to prevent the engine oil from degrading at the higher temperatures.
However, the inventors herein have recognized potential issues with such systems. Using an oil cooler and associated hardware may add weight, complexity, and cost to the vehicle.
One potential approach to at least partially address some of the above issues includes a system and method for a turbocharger which cools lubricant for an engine. The turbocharger comprises a housing and one or more bearing wherein the housing comprises one or more coolant passages and one or more lubricant passages. The coolant passages receive coolant to cool the turbocharger and the lubricant passages receive lubricant to lubricate the bearings. The lubricant is the lubricant for both the turbocharger bearings and the internal combustion engine. The coolant passages and lubricant passages are arranged in the housing to transfer heat from the lubricant in the lubricant passages to the coolant in the coolant passages. The arrangement is configured such that the transfer of heat between the coolant passages and lubricant passages is sufficient to cool the lubricant and maintain the lubricant at a temperature that is suitable for subsequent use in the internal combustion engine.
For example, the turbocharger with coolant passages and lubricant passages may contain coolant from the low temperature coolant circuit and the lubricant may pass through the turbocharger bearings to the engine. The lubricant is thus cooled to a temperature which reduces engine lubricant degradation.
In this way, the turbocharger may provide cooled lubricant to the engine and a separate oil cooler may be eliminated from the system. Thus, the lubricant may be below a temperature threshold, above which the lubricant may degrade.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.